Add-On Section Is Somehow Messed Up

I noticed just today after installing a new theme and working on the site...

  • There's no place to add a new add-on
  • Everything is installed but no option to uninstall (other then accessing settings on some)

Did I do something I'm unaware of? I cleared cache but doesn't seem to help at all including var/cache folder...

This is the screenshot. No "plus" sign to add anything either which did use just few days ago.

Okay that was really weird. I cleared the cache through the admin/storage/ option and seems to work now.

Okay that was really weird. I cleared the cache through the admin/storage/ option and seems to work now.

Right. Sometimes it happens. Clearing cache makes the deal

Hello everyone!

Working on a clone of v4.2.2 in a test environment, the activation of any addon throws a mysterious error notice: "Error Oops, something went wrong (Internal Server Error). Please try again".

I can't find any error logs for this, even the debugger mode doesn't track anything. Most of the addons nevertheless work seamlessly, not however addons related to a customized API extension. When queried, they give "Forbidden: 403" or they simply do not work.

I checked file permissions in the backend, they should be alright as well as the .htaccess file with its rewrite rules...

Thankful for any ideas and suggestions!